Block's free open-source desktop app Bird unifies Claude, Codex, Copilot, Amp, and Goose into one interface. Here's how it works.
What is Bird, and why did Block build it? #
Bird is a free, open-source desktop app from Block, the company behind Square, Cash App, and the Goose coding agent. It works as a single front end for multiple AI coding agent harnesses, including Claude Code, Codex, GitHub Copilot, Amp, Cursor agent, and Goose itself. Rather than juggling separate CLI tools in separate terminal windows, you install Bird once, plug in the harnesses you already pay for, and run all of them through one interface. Block says its own internal teams used the app before releasing it publicly, which is part of why it ships with more personality (and more rough edges) than a typical dev tool.
TL;DR #
Bird unifies coding agent harnesses including Claude Code, Codex, Copilot, Amp, Cursor agent, and Goose into a single desktop app instead of separate terminal sessions.It’s fully free and open source, released under the Apache 2 license, available from bird.xyz or Block’s GitHub repo, and you bring your own subscriptions or API keys.The app runs on the agent client protocol (ACP), meaning any harness that speaks ACP can plug into Bird without custom integration work.** Agents are represented as 3D characterswith names like Birdy, Copycat, Pushback, Choosy, Tinker, and Wildcard, each built around a specific persona and task. Projects tie a folder, context notes, and chat history together**, so an agent can work against a real codebase with persistent instructions rather than a blank chat window.** A slash-command skills system**ships with built-ins like agent builder, API and interface design, and Bird help, functioning similarly to skills in Claude Code.The onboarding is aimed at non-developers as much as engineers, with role-based agent recommendations and an agent builder that avoids hand-written system prompts.
Remy doesn't write the code. It manages the agents who do. #
Remy runs the project. The specialists do the work. You work with the PM, not the implementers.
How does Bird actually work? #
When you open Bird for the first time, it walks you through a short onboarding flow. It asks what kind of work you do, offering categories like engineering, legal, marketing, product, design, and writing. Based on your answer, it recommends a small starter set of agents. A generalist, a builder, and a reviewer role appeared during one walkthrough of the app, each represented by a different 3D character.
After that, Bird prompts you to install the actual agent harnesses: Claude Code, Codex, Copilot, Amp, and Cursor agent, alongside Goose. You pick which ones you want and Bird handles installation. This step isn’t guaranteed to be smooth. Claude Code installation failed during one testing session with a generic “setup hit a snag” message and no clear error detail, though Bird did offer a “troubleshoot in chat” option. Codex installed without issue in the same session.
The technical layer underneath all of this is the agent client protocol, or ACP. Bird talks to each harness through ACP adapters, meaning any coding agent that implements the protocol can theoretically plug into the app without Block needing to build a bespoke integration for every tool. When Codex was installed, Bird pulled in a Codex ACP adapter into its app data folder, which is the visible evidence of this architecture in action.
Once set up, you land on a home screen built as an open canvas rather than a typical chat window or IDE layout. Agent characters wander around the screen, and you can drop in small widgets like an analog clock. The actual work happens in a chat box at the bottom, where you select which harness to run (Goose, Claude Code, Codex, Copilot, Amp, or Cursor agent) and which model to use within that harness. With Codex specifically, the model picker exposes the full range of available GPT model variants along with a reasoning effort slider, letting you dial reasoning up or down directly in the UI rather than through a config file or flag.
What are Bird’s agent personas and how do they differ from a normal chatbot? #
The core organizing idea in Bird is the agent persona: a pre-configured character with its own instructions, its own model choice, and a specific job. Several ship by default:
Birdy helps you work with Bird itself. Copycat is designed to learn your writing style over time so its output doesn’t read as obviously AI-generated. Pushback acts as a critical reviewer you hand drafts to for scrutiny. Choosy helps you weigh decisions without making the choice for you. Tinker builds new agents and skills on request. Wildcard is built to produce unconventional ideas you might not generate on your own.
Other agents start typing. Remy starts asking. #
Scoping, trade-offs, edge cases — the real work. Before a line of code.
You can chat with any of these directly, or pull one into an existing conversation by @ mentioning it. For anything the defaults don’t cover, an agent builder lets you create a custom persona conversationally rather than by writing a system prompt from scratch. That detail matters for the app’s target audience: it removes the main technical barrier that keeps non-developers from customizing AI agent behavior.
How do Projects and Skills work in Bird? #
Projects in Bird bundle three things together: a name, a folder on disk, and a context description of what the project is about. You can also assign a custom icon and color to each one, which is a minor touch but helps with visually distinguishing projects on the canvas.
In practice, a project gives an agent persistent grounding. Rather than re-explaining your goal in every chat, you write the context once (for example, describing a web app for writing and sharing movie reviews with exportable images) and every conversation inside that project inherits it. When a coding agent like Codex is set loose inside a project folder, it behaves like an actual coding agent rather than a chatbot: it inspects the workspace, checks whether it’s a Git repository, plans a build strategy, and asks clarifying questions before writing code rather than guessing. In one demonstrated session, Codex explicitly asked whether movie data should come from a built-in catalog or a live API requiring a key, and flagged that live comparisons during development would use more tokens, which is a useful bit of transparency for anyone watching their usage.
Skills are Bird’s system for reusable instructions, triggered by typing a slash command in the chat box. Out of the box, Bird includes skills like an agent builder, API and interface design help, an “avant-garde front end” skill, and general Bird help. Functionally, these work much like the skills system in Claude Code: instructions that get pulled into context automatically when relevant rather than being pasted in manually every time.
Is Bird worth using if you’re already paying for Claude Code or Codex? #
If you already have an active subscription or API key for Claude, Codex, Copilot, Amp, or Goose, Bird costs nothing extra to try, since Block doesn’t charge for the app itself. For that audience, it functions as a nicer window into tools you’re already using rather than a new subscription to justify. The main value is consolidation: one interface, one place to switch models and harnesses, and shared concepts like projects and skills that work across whichever backend you pick. Where it’s less clearly a win is for people already comfortable living in a terminal. Bird’s canvas, wandering characters, and onboarding flow are aimed squarely at making CLI-based agents approachable for non-technical users. Power users who just want a fast, minimal interface to a coding agent may find the visual layer gets in the way rather than helping.
It’s also worth treating this as a first release. Installation issues (Claude Code failing to set up in one test) point to expected rough edges in a brand-new open-source tool. Given that Block reportedly uses Bird internally, ongoing updates seem likely, but anyone trying it today should expect some friction.
Frequently Asked Questions #
What coding agents does Bird support?
Everyone else built a construction worker.
We built the contractor.
One file at a time.
UI, API, database, deploy.
Bird supports Claude Code, Codex, GitHub Copilot, Amp, Cursor agent, and Goose, Block’s own agent. You choose the harness and model per conversation rather than being locked into one.
Do I need to pay Block to use Bird?
No. Bird itself is free and open source under the Apache 2 license. You need your own subscriptions or API keys for whichever underlying agent harness you want to use.
What is ACP and why does it matter for Bird?
ACP stands for agent client protocol. It’s the communication layer Bird uses to talk to different coding agent harnesses. Because Bird is built around ACP rather than one specific tool, any agent that implements the protocol can plug into the app.
Is Bird meant for developers only?
Not exclusively. The onboarding asks about your role (engineering, legal, marketing, product, design, writing) and recommends agent personas accordingly, and the agent builder lets non-technical users create custom agents without writing a system prompt by hand.
Where can I download Bird?
Bird is available from bird.xyz or from Block’s GitHub repository, where the source code is published under the Apache 2 license.